Paper AS+SS-WeA11
Optimizing the TOF-SIMS CsM⁺ Depth Profile of a Tunnel Magneto Resistance (TMR) Structure

Wednesday, October 21, 2015, 5:40 pm, Room 212D

Used now for many years in modern magnetic recording devices, TMR sensors consist at their heart of a complicated series of layers, mostly metallic, ranging in thickness from less than a nm to several nm. In order to use the potentially better depth resolution and sensitivity of a SIMS depth profile over other surface analytical techniques, CsM⁺ profiles were obtained using a variety of conditions. The ratio of the sputter ion to primary ion fluences, the sputter ion beam energy, and the % of Cs in a combined Cs/Xe sputter ion beam were all varied, and the results for a single wafer compared. In addition to changes in various CsM⁺ ion intensities and therefore their signal to noise, the Cs/Xe ratio sometimes had unexpected effects on the profile shapes. The primary ion beam fluence was lessened by increasing its raster size over more than the crater bottom. Depth profiles were then created retrospectively from the raw data, using the results themselves to select the flattest portion of the crater bottom.